For vehicles for working mines or quarries, or for use on construction sites, such as loaders, dumpers or scrapers, it is known that the loads borne by each tire vary substantially according to the conditions of use since these vehicles travel at times with a light load (“empty”) and at times with a full load (“full load”). In such cases, the variations in load on the tires may be from 40% to 80% of the rated load defined for the dimension in question by E.T.R.T.O. (The European Tire and Rim Technical Organisation) Standards.
These two extreme conditions of use result in forms of contact patch of the tire with the roadway which are also very variable since it is possible to change from a substantially rectangular overall form to a form which is no longer substantially rectangular. In this latter case, the contact patch has a rectangular median part extended axially on either side by substantially trapezoidal forms (see FIG. 1).
It has been noted that these variations in contact geometries combined with the elements in relief of the tread result in the occurrence of vibrations during rolling of the tire. This is because the ridges of the tread pattern elements may have orientations close to or identical to the orientation of the ends of the contact patches on the edges.
In order to reduce this drawback, means have been sought time and again in the prior art to limit the variations in contact patch geometry under different load conditions.